/Engine/Source/Runtime/MovieSceneTracks/Public/Systems/MovieSceneBlenderSystemHelper.h
Accumulate a value on top of already accumulated values
static void AccumulateResult ( [TSimpleBlendResult](API\Runtime\MovieSceneTracks\Systems\TSimpleBlendResult)< PropertyType > & InOutValue, typename [TCallTraits](API\Runtime\Core\GenericPlatform\TCallTraits)< PropertyType >::ParamType Contributor )